(Table 1) Total organic carbon, calcium carbonate and nitrogen at DSDP Holes 80-559 and 80-550B

Concentrations of organic and inorganic nitrogen have been measured on Leg 80 sediments. The inorganic nitrogen content is relatively constant, 0.02-0.03 wt.%. Because most of the inorganic nitrogen occurs as NH3 or (NH4)+ fixed on clays, clay-poor sediments have lower inorganic nitrogen contents. Organic nitrogen content depends upon both the type and the quantity of organic matter present. In Leg 80 sediments, woody kerogens contain much less organic nitrogen than do kerogens of algal origin. Furthermore, pelagic samples of low organic carbon content have less organic nitrogen than predicted, because of loss during diagenesis. DSDP shipboard analytical procedures do not distinguish between organic and inorganic nitrogen. Great caution must therefore be exercised in interpreting C/N ratios.